Hi Marco, it is intended that MoI v4 will have a high amount of compatibility with v3. The main thing that you'll have to watch out for is UI customizations. The v4 UI can be customized similarly as v3 but the structure of the UI is slightly different since v3 used an older version of the WebKit flexbox for arranging things and v4 uses the newer standardized flexbox. It's only pretty slight differences but you'll generally need to merge any UI customizations into the new v4 structure rather than just copying the entire v3 .htm UI files (like SidePane.htm and CommandBar.htm) over directly.


For your specific points:

> 1) Scripts.
> The new API core (if there is a new one) will be backward compatible with the current API ?
> All the Scripts written for V3 will continue to work properly on V4 ?

There is a new implementation for the internal bridging between C++ code and script, but it presents all the same properties and object model as v3 so in general V3 scripts should run in V4. There may be some differences from in how exceptions are thrown for errors in a couple of spots and so it's possible that a few scripts may need slight adjustments to a couple of lines of code (or I'll tune up the engine behavior to make it compatible) but I think that will be pretty rare.

The threading model for scripts is different in v4, in v4 command scripts will run on the main thread rather than running in moi_commandprocessor.exe and doing interprocess communication. This should be for the most part be transparent to script but also may be a source of slight differences for how exceptions are thrown.


> 2) .3dm file format
> Moi V4 will use by default the Rhino 5 format instead of Rhino 4 ?

No, this is the same as MoI v3. It will save to Rhino 5 format if you have opened a Rhino 5 .3dm file. If you have made a new file in MoI then it's saved as a Rhino 4 file.


> 3) Html files.
> The new V4 will accept all custom html files used to customize V3's UI ?

This is the area where you'll have to watch out - the V4 html files are slightly different from v3 and so you can't just copy an entire customized v3 UI in place of the v4 UI files, you'll need to merge your changes into the new v4 structure. The same thing applied to the transition from V2 to V3 and will probably continue to be the case between major versions until I'm able to make it more modularized.


> 4) Shortcuts
> Can I use with V4 all the hotkey setup that I currently use for V3 ?

Yup, this should be directly compatible. Moi v4 will use the same moi.ini file as v3 and so your shortcuts should just be there and work the same. In v4 the shortcut keys section of the Options dialog has been tuned up so that when you add in a new shortcut key you define it by pressing the actual key combo instead of typing in text like "Ctrl+A".

- Michael